442 Prof. Meyen's Report on the Progress of 



of Marquart. The observations of the latter on this subject 

 are however much more accurate than those of Dr. Hope; 

 Marquart showed, for instance, that the Xanthogene is pro- 

 duced from a blue extractive substance converted to red by 

 an acid, &c. It also appears from the statement of Dr. Hope 

 that he made no use at all of the microscope, which however 

 was quite necessary. One consequence of this is the retaining 

 of the term Ckromule, which De Candolle had proposed for 

 the colouring matter of plants; against the adoption of which 

 however many reasons exist. Dr. Hope states that he found 

 that the Xanthogene occurs independently of the Chlorophyll 

 in all green leaves; that in white flowers (about thirty different 

 ones were examined) Xanthogene only is contained, exactly as 

 in the yellow flowers, where also no Erythrogene occurs. The 

 explanations of this are to be found, I think, in the experi- 

 ments of Marquart. Red flowers on the contrary exhibited 

 Erythrogene, as also Xanthogene, as did blue, purple, and 

 orange flowers, &c. 



I believe, judging from my own observations, that the work 

 of Marquart deserves the preference in every respect; also 

 that his names, on account of priority even, should be re- 

 tained. Marquart's memoir is not mentioned, although it 

 might have been well known in England*. 



Hunefeld has published f a very interesting paper on the 

 blue colours of the flowers of plants; the subject is however 

 treated more in a chemical view; therefore we can only call 

 attention to it. Hunefeldt also proposes the use of water 

 acidulated with sulphuric acid, as a means of facilitating the 

 microscopical examination of the coloured parts of vege- 

 tables. 



F. Schulze § has made some observations on the Amylum of 

 the potato, and has confirmed some of the most essential points 

 of the results which Fritzsche obtained in his experiments on 

 this subject. As such, I will mention the following: The 

 composition of the Amylum globule from concentric layers 

 deposited round a certain point, called the nucleus, and the 

 changes which the Amylum globule undergoes in consequence 

 of growth; its solution from the interior as well as at the sur- 

 face. Schulze directs attention to the fact, that we are ac- 



* [It is to be regretted that the little encouragement given to the pub- 

 lication of notices of foreign discoveries in this country gives rise to fre- 

 quent remarks of this kind. — Edit.] 



t Additions to the chemistry of vegetable colours. — Erdmann and Schweig- 

 ger-Seidel's Journ.fur Prakt. Chem., ix. p. 217—238. X Ibid., p, 238. 



X On the Metamorphosis of Amylum. Poggendorlf's Ann., vol. xxxix. 

 p. 489-493. 



